Reproductive Hormones in the Menstrual Cycle

Introduction

• Hormones are chemical messengers produced by glands and carried by the bloodstream to specific organs.
• During puberty, hormones cause physical and emotional changes.

Puberty

• Testosterone: Produced by testes, stimulates sperm production in males.
• Oestrogen: Produced by ovaries, regulates menstrual cycle in females and causes eggs to mature.
• Changes during puberty:
  • Boys: Voice breaks, facial and body hair grow, body becomes muscular, testes produce sperm.
  • Girls: Voice deepens gradually, hips widen, breasts develop, ovaries release eggs leading to menstruation.
  • Both: Growth of pubic and underarm hair, development of sexual organs.

Menstrual Cycle

• Recurring event in the female reproductive system, approximately 28 days long.
• Involves preparation of the uterus lining for pregnancy.
• If no implantation occurs, the uterus lining is shed (menstruation).

Hormones Involved in the Menstrual Cycle

1. FSH (Follicle Stimulating Hormone)
   • Produced by the pituitary gland.
   • Stimulates egg maturation in ovaries and release of oestrogen.
2. Oestrogen
   • Produced by ovaries.
   • Inhibits production of FSH, ensuring only one egg matures.
   • Repairs and maintains uterus lining, stimulates release of LH.
3. LH (Luteinising Hormone)
   • Produced by the pituitary gland.
   • Triggers ovulation (release of a mature egg).
4. Progesterone
   • Produced by ovaries.
   • Maintains the uterus lining, particularly important during pregnancy.

Pregnancy

• If pregnancy occurs, the placenta produces progesterone.
• This maintains the uterus lining throughout pregnancy, preventing menstruation.

Conclusion

• Hormones play a crucial role in regulating the menstrual cycle and reproductive functions in humans.

Additional Resources

• Coordination and control - the nervous system - AQA
• Coordination and control - the human endocrine system - AQA
• Sample exam questions - homeostasis and response - AQA